The car in question is a s2 turbo, a week ago when i was driving as the turbo began to kick in i heard a really loud POP from the engine followed by a gust of black smoke. Now when i drive the car as the revs approach 2-3000 the turbo does not kick in and the exhuast becomes alot louder (almost like a afterburner sound). The dump valve still works fine and drives perfect up until 3000revs. I have no idea about turbos but am wanting to learn about them, can anyone plz advise me what the problem is , a cure and roughly the cost?? Many thanx Lee